I am now thinking a ship could use maglev energy to achieve near escape velocity at ground level, by trapping a ball of plasma from the heat shield and insulating the craft. However a very dense power supply would allow the craft to accelerate using the heat shield plasma as propellant.

The problem at ordinary ground level is that of air resistance i could see maglev being of use to accelerate to scramjet speeds in a hybrid system but even tho i believe we may one day get the quality control on carbon nanotubes to a level that a space elevator maybe one day be built. I think the kind of materials tech that you would need to go hypersonic at ground level would greatly surpass even a 36000 kilometre nanotube in levels of unobtainium with the heat and turbulence you would cause at ground level at those speeds. The Americans did not like us flying Concorde at great height over most of their country and that was only Mach2 not Mach25 so you might have problems placing it as well.

I do however like the bridge into space story as i think it was done well enough to show that it is no longer even much of an engineering problem its more of an economic and political one but unfortunately in this world politicians and economists tend to trump engineers in access and allocation of resources.

_________________Someone has to tilt at windmills.So that we know what to do when the real giants come!!!!

That is why you maintain a repelling field on the plasma, pushing it so it does not contact the surface once a virtual shield of plasma is formed. This would require a sacrificial rod that is replaced when near depleted. This rod would gradually push out in the center of the heat shield at the very tip of the craft, by combining this with a plasma engine that was fed plasma from the heat shield allowing you to counter friction.A very dense power supply would be essential. This two stage launchcraft could be made to cost little per launch.

I am calling it project Mariah.

Models math and a drob box soon.

_________________Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore.

That is why you maintain a repelling field on the plasma, pushing it so it does not contact the surface once a virtual shield of plasma is formed. This would require a sacrificial rod that is replaced when near depleted. This rod would gradually push out in the center of the heat shield at the very tip of the craft, by combining this with a plasma engine that was fed plasma from the heat shield allowing you to counter friction.A very dense power supply would be essential. This two stage launchcraft could be made to cost little per launch.

I am calling it project Mariah.

Models math and a drob box soon.

I have seen lasers used to measure the the distortion of the atmosphere to enable corrective optics but i suspect that the amount of energy you would need to dump into the atmosphere to maintain a plasma tunnel that would reduce friction sufficiently would have energy costs greater than more traditional approaches this is only an intuitive guess based on my limited experience so i would be happy if proven wrong but you may also suffer from artificially created lighting strikes. And some of the other side effects may upset the neighbours even more that of supersonic or hypersonic launches.

I really do think your energy bill will be quite eye-watering unless some of the latest cold fusion ideas really are proven to be true and even then the gigawatt or maybe even terrawatt toys you want to play with to make your idea succeed are unlikely to be in production for a decade or more.

_________________Someone has to tilt at windmills.So that we know what to do when the real giants come!!!!

The energy here that is most significant in the process is on the ground. Now as far maitaining plasma, simply by restricting it from getting out of the way of the incoming mach speed air, the plasma would not be made in front of the ship, but rather on the heat shield only for a moment, then you confine the plasma like a plasma window, this would stay super hot and not contact the ship. The insane amount of energy here is friction on the plasma, so if work could be extracted by having a highly energetic input stream, and turning some of its heat into motion, (Vasimir) you could propel the craft. Adding tritium or another fusion fuel at insane speeds could make an orion class ship, with no fission.

_________________Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore.

the plasma would not be made in front of the ship, but rather on the heat shield only for a moment, then you confine the plasma like a plasma window, this would stay super hot and not contact the ship. The insane amount of energy here is friction on the plasma, so if work could be extracted by having a highly energetic input stream, and turning some of its heat into motion, (Vasimir) you could propel the craft. Adding tritium or another fusion fuel at insane speeds could make an orion class ship, with no fission.

I assume this heat shield is on the front of the ship? Remember Newton? your plasma window is going to be pushing against the rest of the atmosphere you will still suffer from considerable air resistance losses even if you benefit from low turbulence and get some extra isp from accelerating the plasma.

I had thought initially from your descriptions you were using energy on the ground to punch a plasma "hole" thru the atmosphere and then send your vehicle magnetically climbing it.

_________________Someone has to tilt at windmills.So that we know what to do when the real giants come!!!!

the plasma would not be made in front of the ship, but rather on the heat shield only for a moment, then you confine the plasma like a plasma window, this would stay super hot and not contact the ship. The insane amount of energy here is friction on the plasma, so if work could be extracted by having a highly energetic input stream, and turning some of its heat into motion, (Vasimir) you could propel the craft. Adding tritium or another fusion fuel at insane speeds could make an orion class ship, with no fission.

I assume this heat shield is on the front of the ship? Remember Newton? your plasma window is going to be pushing against the rest of the atmosphere you will still suffer from considerable air resistance losses even if you benefit from low turbulence and get some extra isp from accelerating the plasma.

I had thought initially from your descriptions you were using energy on the ground to punch a plasma "hole" thru the atmosphere and then send your vehicle magnetically climbing it.

You'd also be expanding the plasma in front of the ship, which would create negative lift, or drag if you're trying to go up. That's why they use this technique for braking on the way down. You can't reverse it. You'd be using more energy than you get out of it, this bootstrapping is essentually a plasma-dynamic perpetual motion machine. You'd be reversing Entropy, one of the fundamental principles of thermodynamics. It can't work in this universe.

_________________"You can't have everything, where would you put it?" -Steven Wright.

The fact remains, that friction induces heat and that heat changes the state of the state. Once this plasma layer is formed, it can be repelled, so its taking the heat Instead. Plasma can be made to change heat into motion. This is not perpetual motion, A very dense power supply would be needed to power the plasma accelerator that is fed the heat shield plasma, also a large amount of energy would be needed to repel the plasma, that is generated by a sacrificial rod that extends out from the center of the heat shield gradually contacting with the mach speed air.

I am looking for processes that require super hot plasma that output power, and fusion is all I can think of, breakeven would be easier in this instance as a hot plasma would be the output, instead of changing heat to electricity.

A craft that could be launched at mach speed at ground level could use the plasma as a reaction mass, alsmost like a plasma ram jet. When the plasma is pinched to its smallest point, add tritium.

_________________Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore.

The fact remains, that friction induces heat and that heat changes the state of the state. Once this plasma layer is formed, it can be repelled,

Mine and Psi's point was that you repelling the plasma is going to have it push against the rest of the atmosphere which would need considerable amounts of energy to do so and even more to overcome in the other direction than i would think than needed to do the same payload with traditional rocketry but if you are basically building an Orion project rocket using fusion bombs rather than fissile bombs and the plasma is just for local shielding i can see where you think your going to get your energy from but i doubt many governmental authority's would allow you to have a go in their jurisdictions as even the peaceful Orion project fell foul of several international arms treaty's.

_________________Someone has to tilt at windmills.So that we know what to do when the real giants come!!!!

The idea is not a fusion bomb...... but rather using the high energy latent in the plasma to initiate a reaction that requires a high threshold to release even more energy. By adding heat to the plasma through fusion etc. you could then use wakefield acceleration to turn the heat into motion with Radio frequency like vasimr. That is not perpetual motion, its exploiting what is normally a total loss.... friction.And the more focused the field is in the right places, your only pushing a small cross section.I know the idea is out there a little, but it exploits the intense conditions to both insulate and propel the ship.... not accelerate so much as it would keep the momentum it had from launch.

_________________Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore.

Last edited by Sigma on Thu Jun 07, 2012 7:11 pm, edited 1 time in total.

I was thinking along my own lines, but I think this solves all issues, a dense power source that would love preheated plasma, to exchange heat into its D-T precatilist cathode stage! And it would require a very large magnetic confinement, the plasma shield repulsior would be the outside of the confinment, pressing on this field with plasma would make a rise in current, and field denisty, like in a emp pinch device

_________________Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore.

I've been thinking about this for a while and wanted to add what I hope are complimentary ideas.

I used to be hopeful about space elevators, but never could see a feasible plan for transporting the energy up to the climber mid-way, nor a way to avoid micrometeors; plus, the ascent would be really slow. Then I realized that once you have full carbon nanotube technology, enough to build an elevator with, you could instead spool them onto flywheels levitated about their axis, and now you have a convenient way to store lots of energy for an electromagnetic launch, before transferring it to capacitor and thence to electromagnets. Flywheel storage is very efficient, and carbon nanotubes flywheels can be spun faster for high power density. So if you can build a space elevator, you can build a power system for a space railgun, with greater launch speed & less risk.

Second thought: you can minimize drag by having a very narrow and pointy projectile, indeed the more tubelike the better, then you have the same frontal surface area and more weight. Alternately, the projectile could be a hollow cylinder aka "Busemann's biplane" (http://en.wikipedia.org/wiki/Busemann's_Biplane), which would elminate the sonic boom of launch, though it would require arranging the cargo around the thicker center part and a wider launch tube.

Third: I love the idea of a second railgun in orbit, which obviously is easier to build once you reduce earth launch costs. I don't see a problem with needing its own thrusters to deal with recoil; the railgun mass would be huge compared to each projectile, so its delta-V and orbital change is small, and doesn't need to be corrected right away. It can use efficient ion engines, powered by solar cells, to return to its initial orbit before the next use. You can also use it in reverse to slow down an orbiting payload before reentry. If you can reduce the payload to an effective stop, it might reenter with a very modest heat shield followed by a glider landing, much safer than the shuttle like the shuttle but slower and hence safer. I also picture a series of space railguns; one in LEO which could boost a payload to GEO or a transfer orbit, then one that takes you to lunar orbit, from there one that gives a further push to the inner or outer solar system, etc.

I used to be hopeful about space elevators, but never could see a feasible plan for transporting the energy up to the climber mid-way, nor a way to avoid micrometeors; plus, the ascent would be really slow. Then I realized that once you have full carbon nanotube technology, enough to build an elevator with, you could instead spool them onto flywheels levitated about their axis, and now you have a convenient way to store lots of energy for an electromagnetic launch, before transferring it to capacitor and thence to electromagnets. Flywheel storage is very efficient, and carbon nanotubes flywheels can be spun faster for high power density. So if you can build a space elevator, you can build a power system for a space railgun, with greater launch speed & less risk.

Hi Scott welcome to the forum.

I am still hopeful about space elevators especially now that carbon nanotubes can be made in meter lengths with no defects micro meteors could still be a problem tho one that might be overcome the way Victorian engineers dealt with problems by over specifying. A slow accent could be a lot more efficient and safer energy wise than a rail gun in the atmosphere. But i do like the idea of CNT flywheels and we could come to a compromise a slow accent straight up the elevator for 200Km then have a space rail gun to accelerate you in fairly hard vacuum to orbital or above speed, who says you have to get off at the top floor Solar panels charging CNT flywheels might be a part of the launch mechanism. I think solar and lasers could power a elevator easily 200Km.

_________________Someone has to tilt at windmills.So that we know what to do when the real giants come!!!!

micro meteors could still be a problem tho one that might be overcome the way Victorian engineers dealt with problems by over specifying. A slow accent could be a lot more efficient and safer energy wise than a rail gun in the atmosphere. But i do like the idea of CNT flywheels and we could come to a compromise a slow accent straight up the elevator for 200Km then have a space rail gun to accelerate you in fairly hard vacuum to orbital or above speed, who says you have to get off at the top floor Solar panels charging CNT flywheels might be a part of the launch mechanism. I think solar and lasers could power a elevator easily 200Km.

Overspecifying can work if done the right way. But the obvious manner of doing this for conventional projects--just making the cable thicker--won't work here, since it wouldn't take a large micrometeor to slice through any reasonably sized cable. I've heard of ideas for some kind of net or web but surely under tension the center would just contract essentially to a line again. The kind of redundancy you need is multiple parallel cables, but then they need to be kept apart so they aren't entangled, perhaps using rigid rings every few kilometers. I'm not sure this wouldn't work, but it does add weight and complexity.

I'm not sure slower is better; the longer you're ascending the more things that can happen to you along the way; you don't want a slow ascent through the radiation belts.

Combo systems might be possible, though it seems that would mean that the upper railgun is not actually in orbit; are you envisioning that it is itself suspended by multiple cables from a much higher orbiting counterweight, then a further cable going from the ground to one end of the railgun? Of course this means lots of cables and a large structure further out. Alternately, we could use a much smaller ground-based railgun that only accelerates the payload up 200km and at 1-2 km/s, where it meets a moving but slower-than-orbit railgun; then the counterweight doesn't need to be quite so high and large, and the orbiting railgun smaller.

There might be some use in thinking about these alternatives, but given that ground-based systems will always have cheaper electricity and lower maintenance costs, I'm not sure that it wouldn't be better to put as much as the system there as possible.

I am not sure if I will ever find someone to test my plasma supercavity idea, but I am pretty sure something that exploits the normal weaknesses of a system and makes them strengths.... Also I believe that a plasma or a dusty plasma fusion rocket can be made with no fission products, maybe like a plasma pulsejet that rams plasma into a hollow center chamber, add hydrogen isotopes, pinch it with Z, and then open a shutter, virtual or solid, and thrust, repeat, breakeven here is easier because there is no capture system, just a nozzle, and an m.h.d. that is the actual shutter? Use induction to generate power to ram the plasma, charge a massive capacitor bank, open the rear shutter and pow!

This set up would work best if it was very heavy, from a momentum standpoint, So the overall plasma drag, and thrust impulse moments would not cause as much uneven acceleration on the crew etc.

If you knew how long the cycle was, you could have multiple engines, one inside of the other, and have them offset, so the overall acceleration could be more even. Engine 1 is firing while engine 2 is ramming.

The whole skin would have to be easily replacable because of runaway electrons and evaporation, and the leading edge of the tube could be replaced each after landing, as it would take almost all the friction. The same scheme that makes the plasma bubble could also insulate the inside of the tube,

_________________Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore.